For treating diseases of the eye, it is known to direct the rays of a laser light source onto the eye of a patient with the use of ophthalmic viewing apparatus. Apparatus for laser treatment of the eye are disclosed, for example, in U.S. Pat. No. 3,720,213. It is a disadvantage of these known apparatus that they are designed as single-purpose devices for laser therapy and therefore the acquisition of a complete, complex apparatus is required for this purpose.